Science Buddies: "Ask an Expert"

I have did everything in the directions and i still get noting reading from the multimeter.
i need help please because i dont know what im doing wrong.
i have read all the post on here and i still cant get it to work

Hi chrissy57,

Welcome to the forum. Have you seen this background info for understanding what the multimeter measures and troubleshooting your problems?

https://www.sciencebuddies.org/science- ... ntro.shtml
https://www.sciencebuddies.org/science- ... eter.shtml

It's hard to tell you what might be wrong without knowing what settings you have tried. If the info above doesn't help you figure out the problem, it would help if you could post a photo of your multimeter with good enough resolution for us to read the labels of the different settings.

Amanda

chrissy57 - There seems to be a lot of difficulty with this experiment. I think it is mostly from not understanding how the multimeter works and what the appropriate settings are for low DC current measurement. The connections between battery, meter and probes are very simple and are shown in the description. I have responded to several people that have had difficulties and have provided a link to one of my earlier responses. If you are still having setup problems to get any readings after you have reviewed this, send another response, we'll get you to success.

Rick Marz

https://www.sciencebuddies.org/science- ... =26&t=7040

Hello there!
I'm also busy conducting my experiment with this electrolyte challenge..(by the way-it is indeed a challenge!!)
I really just want to know why the conductance sensor is necessary?? I already did my experiment and everything but my multimeter wasn't the right one.
(I just got another multimer so I really hope that everything will work now!)
I couldn't see the difference with or without the sensor..so mayby I did something wrong? I don't know..

I hope that you can be of some help pleeeeaaassseee!

thank you vey much
Maderie

The information, on the right, about the project i want to do is not correct.. I first wanted to do that project idea, but i changed from projects.

I am also doing this project as well, and im confused with the method of this experiment. Where does the Negative (black) lead of the 9v Battery, lead to? It doesnt say anything about it in the method and the picture (Figure 2) confuses me even more. please help me! where does the black lead go to!

The schematic (left side of Figure 2) shows:
1) The negative lead from the battery hooked to one end of the conductivity probe.
2) The other end of the conductivity probe is hooked to one of the uA (or mA) current meter leads
3) The positive lead from the battery is hooked to the other uA (or mA) current meter leads
Because the schematic doesn't label the + and - leads of the meter, there are two interpretations of the intent.

The picture (right side of Figure 2) shows:
1) The black (negative) lead from the battery hooked to the red (positive) current meter lead
2) The black (negative) lead of the current meter hooked to one end of the current probe
3) The other end of the current probe hooked to the red (positive) lead of the battery
Note: The picture is inconsistent with either interpretation of the schematic.

Bottom line, it really doesn't matter what order or which meter lead or which battery lead is used for which connection (except for whether the meter reads +/-) in this circuit. What matters is that the meter, battery, and current probe are all in a single series loop circuit.

Pick a battery lead, connect it to one end of the current probe. Connect the other end of the battery to a current meter lead. Connect the other current meter lead to the other end of the current probe. If you don't like the meter polarity reading, switch the meter leads.

EVEN SIMPLER CIRCUIT:
A different way to measure the conductance is to eliminate the battery. Put the meter on one of the Ohms scales, connect the meter leads to opposite ends of the conductance probe. Measure the resistance of each solution. The resistance is the mathmatical reciprical of the conductance.

Craig_Bridge wrote:meter leads to opposite ends of the conductance probe. Measure the resistance of each solution. The resistance is the mathmatical reciprical of the conductance.

The problem is we are using a DC current which polarises the solution and electrodes dissolve as an electrolytic cell is set up. Direct resistance measurement did not work for me.

gajanan78 wrote:Direct resistance measurement did not work for me.

Can you discribe what happened with direct resistance readings?

gajanan78 wrote: electrodes dissolve

means you have a chemical reaction going on. The original experimental setup was not designed to deal with chemical reactions.